In manufacturing processes of semiconductor devices, there are some instances where a silicon oxide (SiO2) film is formed on a carbon film and is then patterned.
For example, a SiO2 film may be formed on an amorphous carbon film and is then patterned. The amorphous carbon film may be etched using the patterned SiO2 film.
However, there is a problem that thickness of the carbon film is reduced when the SiO2 film is directly formed on the carbon film. For example, if an atomic layer deposition (ALD) method using plasma with a process temperature at room temperature is used, the thickness of the carbon film is reduced by about 3 to 4 nm If the ALD method using plasma under the same conditions at a process temperature of 300 degrees C. is used, the thickness of the carbon film is reduced by about 5 to 7 nm. One of reasons for this is that carbon on a surface of the carbon film reacts with oxygen (O2) or oxygen radicals (O*) and is then volatilized as CO2 or CO in an initial film forming phase of the SiO2 film.